Herbicidal heterocyclic esters of 2-nitro-5-(o-chloro-p-trifluoromethylphenoxy)-benzoic acid as compositions and herbicidal method

ABSTRACT

Herbicidally effective aminoalkyl esters of 2-nitro-5-(o-chloro-p-trifluoromethylphenoxy)-benzoic acid, and acid addition salts and quaternary ammonium salts thereof, are suitable for the selective control of weeds in crops of useful plants, for example soya bean and rice crops. 
     The aminoalkyl esters correspond to the formula ##STR1## wherein A is a C 2  -C 4  -alkylene bridge or the direct bond, and ##STR2## is an open amino group, and ##STR3## is a cyclic amino group.

This is a division of application Ser. No. 417,744 filed on Sept. 13,1982, now U.S. Pat. No. 4,495,350, which is a division of applicationSer. No. 107,983, filed Dec. 28, 1979, now U.S. Pat. No. 4,455,437.

The present invention relates to novel aminoalkyl esters of2-nitro-5-(o-chloro-p-trifluoromethylphenoxy)-benzoic acid having aherbicidal action, and acid addition and quaternary salts thereof, toprocesses for producing them, to compositions containing them as activesubstance, and to their use as selective herbicides.

The aminoalkyl esters of2-nitro-5-(o-chloro-p-trifluoromethylphenoxy)-benzoic acid correspond tothe formula I ##STR4## wherein A is a branched-chain or straight-chainC₂ -C₄ -alkylene group or the direct bond,

R₁ is C₁ -C₄ -alkyl which is unsubstituted or substituted by halogen,cyano or hydroxyl, or is interrupted by oxygen or sulfur, or it is C₃-C₅ -alkenyl or alkynyl both unsubstituted or substituted by halogen,

R₂ is hydrogen or has the same meaning as R₁,

R₁ and R₂ or R₁ and a carbon atom of A together with the nitrogen atomto which they are bound likewise form a 5-7-membered heterocycle whichcan be interrupted by oxygen, sulfur or >NR₃, and

R₃ is hydrogen, C₁ -C₄ -alkyl, phenyl or benzyl.

Suitable as active substances are also the acid addition salts andquaternary ammonium salts of these aminoalkyl esters, which saltscorrespond to the formula Ia ##STR5## wherein A, R₁ and R₂ have themeanings defined above, R₄ is C₁ -C₆ -alkyl which is unsubstituted orsubstituted by hydroxyl or methoxy, or it is benzyl, and B is the anionof an organic or inorganic acid.

The alkylene groups A in this formula embrace the ethylene, propyleneand butylene groups, such as the branched-chain groups 1-methylethylene,2-methylethylene, 1-methylpropylene, 2-methylpropylene and3-methylpropylene, as well as 1,2-dimethylethylene.

The alkyl groups R₁, R₂, R₃ and R₄ can be straight-chain orbranched-chain, and likewise the alkenyl and alkynyl groups R₁ and R₂.Possible substituents of the groups R₁ and R₂ are halogen atoms,particularly chlorine, bromine and iodine; they can moreover besubstituted by cyano or hydroxyl, or be interrupted by oxygen or sulfer.

Suitable heterocycles are in particular pyrrolidine, pyridine,piperidine, azepine, morpholine, piperazine and thiomorpholine. Theserings can be mono- or disubstituted by C₁ -C₄ -alkyl groups or halogenatoms, or they can also be interrupted by a carbonyl group.

Suitable acids for forming salts are the hydrogen halides, sulfuricacid, organic sulfuric acids, phosphoric acid or organic acids, forexample fatty acids. Suitable for quaternisation are in particular alkylor benzyl halides, as well as alkyl or benzyl esters of toluenesulfonicacid.

2-Nitro-5-(o-chloro-p-trifluoromethylphenoxy)-benzoic acid is known fromthe U.S. Pat. No. 3,928,416. It has a herbicidal action but is fairlyphytotoxic. The aminoalkyl esters and acid addition salts thereofaccording to the invention surprisingly exhibit, whilst having anequally good herbicidal action, valuable selectivity with respect todicotyledonous cultivated plants, especially soya bean plants.

From U.S. Pat. No. 3,784,635 are also known 2-nitro-5-tolueneoxy-benzoicacid esters and amides having a herbicidal action.

The aminoalkyl esters of2-nitro-5-(o-chloro-p-trifluoromethylphenoxy)-benzoic acid of theformula I and acid addtion salts thereof are produced in a manner knownper se.

One process comprises reacting a halide of2-nitro-5-(o-chloro-p-trifluoromethylphenoxy)-benzoic acid of theformula II ##STR6## wherein "Hal" is chlorine or bromine, with theaminoalkanol of the formula III ##STR7## wherein A, R₁ and R₂ have themeanings defined under the formula I.

The reaction is performed advantageously in a solvent inert to thereactants, optionally in the presence of the molar amount of anacid-binding agent, depending on whether it is desired to obtain as thefinal product the aminoalkyl ester or an acid addition salt thereof. Thetemperature of this reaction can vary between room temperature and theboiling point of the reaction mixture.

Some compounds can be produced by firstly reacting the benzoic acidhalide of the formula II with a halogenoalkanol of the formula IV

    HO-A-Hal                                                   (IV)

wherein A has the meaning defined under the formula I, and "Hal" ischlorine or bromine, to give the halogenoalkyl ester of2-nitro-5-(o-chloro-p-trifluoromethyl-phenoxy)-benzoic acid of theformula V ##STR8## wherein A and "Hal" have the meanings given above,and then reacting this product with an amine of the formula VI ##STR9##wherein R₁ and R₂ have the meanings defined under the formula I,optionally in the presence of the equimolar amount of an acid-bindingagent. This process too is advantageously performed in a solvent inertto the reactants, at a temperature between room temperature and theboiling point of the reaction mixture.

Where they do not already occur in salt form from the reaction, acidaddition salts of aminoalkyl esters of the formula I can be obtained ina simple manner by bringing together equimolar amounts of the aminoester and of the acid in an inert solvent.

Conversely, it is possible to obtain from an acid addition salt of thefree amino ester, by the addition of a small excess of a base, best ofall of a tertiary amine, in an aqueous solution in the presence of aninert solvent immiscible with water. The ester passes into the solventphase and can be obtained by evaporating off the solvent.

The quaternary ammonium salts can likewise be obtained by bringingtogether equimolar amounts of the amino ester of the formula I with anester of the formula VI

    R.sub.4 -B                                                 (VI),

wherein B and R₄ have the defined meaning, in an inert solvent; thesalts can subsequently be isolated by evaporating off the solvent.

The production of 2-nitro-5-(o-chloro-p-trifluoromethylphenoxy)-benzoicacid is known, and is described in the U.S. Pat. No. 3,928,416.

The method of producing the aminoalkyl esters of the invention can beseen from the following Examples. The temperatures are given in degreesCentigrade, and percentage values and parts relate to weight. Followingthe Examples, there are listed in a Table further compounds produced inan analogous manner.

The aminoalkyl esters have negligible toxicity for humans and animals,and the handling of them requires no special precautionary measures.They are soluble in the customary solvents, such as hydrocarbons,ethers, ketones and chlorinated hydrocarbons.

EXAMPLE 1 2-Nitro-5-(o-chloro-p-trifluoromethylphenoxy)-benzoicacid-2"-dimethylaminoethyl ester ##STR10##

18.5 g of 2-nitro-5-(o-chloro-p-trifluoromethylphenoxy)-benzoic acid in100 ml of toluene, with 10 ml of thionyl chloride and a drop ofdimethylformamide, is heated at 80° for two hours; the solvent is thendistilled off in vacuo, and the residue is taken up in 50 ml of toluene.This solution of 2-nitro-5-(o-chloro-p-trifluoromethylphenoxy)-benzoylchloride is added dropwise at 20°-60°, with stirring, to a solution of20 g of 2-dimethylaminoethanol and 28 ml of triethylamine in 200 ml oftoluene. After one hour, the reaction mixture is poured into water. Theorganic layer is washed with water, dried, and concentrated byevaporation to obtain, in practically quantitative yield, theabove-given ester in the form of oil, which solidifies after triturationwith hexane, m.p. 73°-75°.

EXAMPLE 2 2-Nitro-5-(o-chloro-p-trifluoromethylphenoxy)-benzoicacid-2"-methylamino-ethyl ester (hydrochloride) ##STR11##

20 g of 2-nitro-5-(o-chloro-p-trifluoromethylphenoxy)-benzoicacid-2"-bromoethyl ester with 2.8 g of methylamine is allowed to standin 300 ml of ether. The course of the reaction is followed by means ofthin-layer chromatography. Further processing consists of stirring thereaction mixture up with a diluted sodium carbonate solution, separatingthe ether layer, and drying it over sodium sulfate. The ether solutionis filtered, and subsequent concentration by evaporation yields the freebase of the title compound in the form of highly viscous oil. Thehydrochloride is prepared by passing anhydrous hydrochloric acid gasinto the ether solution; m.p. 105°.

    ______________________________________                                         ##STR12##                                                                     No.                                                                                ##STR13##                 constantsPhysical                             ______________________________________                                        1    C.sub.2 H.sub.4 N(CH.sub.3).sub.2                                                                       m.p. 73-75°                             2    C.sub.3 H.sub.6 N(CH.sub.3).sub.2                                                                       n.sub.D.sup.23.5 1.5314                        3    CH(CH.sub.3)CH.sub.2 N(CH.sub.3).sub.2                                                                  n.sub.D.sup.24.5 1.5285                              ##STR14##                n.sub.D.sup.22 1.5296                          5    C.sub.2 H.sub.4 N(C.sub.2 H.sub.5).sub.2                                                                n.sub.D.sup.24 1.5350                          6    CH(CH.sub.3)CH.sub.2 N(CH.sub.3).sub.2                                                                  n.sub.D.sup.24 1.5394                          7                                                                                   ##STR15##                                                               8                                                                                   ##STR16##                n.sub.D.sup.23 1.5455                          9                                                                                   ##STR17##                n.sub.D.sup.25 1.5455                          10                                                                                  ##STR18##                                                               11   C.sub.2 H.sub.4 N(CH.sub.2 CHCH.sub.2).sub.2                             12   C.sub.2 H.sub.4 N(CH.sub.2 CCH).sub.2                                    13   C.sub.2 H.sub.4 N(C.sub.2 H.sub.4 OH).sub.2                              14   C.sub.2 H.sub.4 NCHCCH                                                   15                                                                                  ##STR19##                                                               16   C.sub.4 H.sub.8 N(CH.sub.3).sub.2                                        17                                                                                  ##STR20##                m.p. 105°                               18   C.sub.2 H.sub.4 N(CH.sub.3)C.sub.2 H.sub.5                                                              n.sub.D.sup.24 1.5395                          19                                                                                  ##STR21##                m.p. 72-75°                             20                                                                                  ##STR22##                n.sub.D.sup.23 1.5268                          21   NC(CH.sub.3).sub.2        m.p. 106-8°                             22                                                                                  ##STR23##                n.sub.D.sup.25 1.5655                          23                                                                                  ##STR24##                m.p. 95-98°                             24                                                                                  ##STR25##                n.sub.D.sup.23 1.5460                          25                                                                                  ##STR26##                n.sub.D.sup.23 1.5501                          26   C.sub.2 H.sub.4 N.sup.⊕ (CH.sub.3).sub.3 I.sup.⊖                                            m.p. 176-9°                             27                                                                                  ##STR27##                m.p. 143-6°                             28                                                                                  ##STR28##                                                               ______________________________________                                    

Compositions according to the invention which contain as activeingredient at least one compound of the formula I are suitable inparticular for selectively controlling wild grasses, which are difficultto control, in crops of cultivated plants, for example soya bean andcotton, by pre-emergence and especially post-emergence application.

The following test methods serve to verify the suitability of the saidcompositions as herbicides (pre- and post-emergence application).

Pre-emergence herbicidal action (inhibition of germination)

Immediately after sowing of the test plants in seed trays in agreenhouse, the surface of the soil is treated with an aqueousdispersion of the active substance, which has been prepared from a 25%emulsion concentrate, and from a 25% wettable powder containing activesubstances which cannot be produced as emulsion concentrates owing toinadequate solubility. Four different concentration series are used,corresponding to 4, 2, 1 and 0.5 kg of active substance per hectare. Theseed trays are left in the greenhouse at 22°-25° C. with 50-70% relativehumidity, and the test is evaluated after 3 weeks, the results beingassessed according to the following scale of ratings:

1=plants have not germinated or have fully died off,

2-3=very strong action,

4-6=moderate action,

7-8=slight action, and

9=no action (as in the case of untreated control plants).

-=plant not tested at this concentration of active substance.

Post-emergence herbicidal action (contact herbicide)

In this test, the compound No. 1 has been compared with2-nitro-5-(o-chloro-p-trifluoromethylphenoxy)-benzoic acid, known fromU.S. Pat. No. 3,928,416, Example 48=compound A. The results aresummarised in the Table which follows.

A largish number (at least 7) of weeds and of cultivated plants, bothmonocotyledonous and dicotyledonous, are sprayed after emergence (in the4- to 6-leaf stage) with an aqueous active-substance dispersion indosage amounts of 0.06, 0.125, 0.25, 0.5, 1, 2 and 4 kg of activesubstance per hectare, and they are then kept at 24°-26° C. with 45-60%relative humidity. The test is evaluated 15 days after treatment, andthe results are assessed according to the same scale of ratings as thatused in the pre-emergence test.

    ______________________________________                                        Compound tested  No. 1       A                                                Amount applied in kg/hect.                                                                     4     2     1   1/2 4   2   1   1/2                          ______________________________________                                        plant                                                                         soya bean        8     8     9   9   3   4   5   5                            wheat            3     7     8   9   2   4   4   8                            maize            3     5     9   9   1   2   3   3                            abutilon sp.     1     1     1   2   1   1   1   2                            sesbania exaltata                                                                              1     1     1   2   1   1   1   1                            amaranthus retroflexus                                                                         1     1     1   1   1   1   1   1                            ipomoea purpurea 1     1     1   2   1   1   1   1                            ______________________________________                                    

The novel active substances of the formula I are stable compounds whichare soluble in customary organic solvents, such as alcohols, ethers,ketones, dimethylformamide, dimethyl sulfoxide, and so forth.

The compositions according to the invention are produced in a mannerknown per se by the intimate mixing and grinding of active substances ofthe general formula I with suitable carriers and/or distributing agents,optionally with the addition of antifoaming agents, wetting agents,dispersing agents and/or solvents, all inert to the active substances.The active substances can be obtained and used in the following forms:

solid preparations: dusts, scattering agents, granules, (coatedgranules, impregnated granules and homogeneous granules);

water-dispersible concentrates of active substance: wettable powders,pastes, emulsions and emulsion concentrates; and

liquid preparations: solutions.

The concentration of active substance in the compositions according tothe invention is 1 to 80 percent by weight, and when being applied thecompositions can if necessary contain the active substances also at alower concentration, such as about 0.05 to 1 percent by weight.

Other biocidal active substances or compositions can be mixed with thedescribed compositions according to the invention.

The following formulation examples are intended to further illustratethe production of solid and liquid preparations.

Emulsion concentrate

The following constituents are mixed together to produce a 25% emulsionconcentrate:

25 parts of an active substance of the formula I,

5 parts of a mixture of nonylphenolpolyoxyethylene or calciumdodecylbenzene sulfate,

15 parts of cyclohexanone, and

55 parts of xylene.

This concentrate can be diluted with water to give emulsions of suitableconcentration, for example 0.1 to 10%, and emulsions of this type aresuitable for controlling weeds in crops of cultivated plants.

Granulate

The following substances are used to produce a 5% granulate:

5 parts of one of the active substances of the formula I,

0.25 part of epichlorohydrin,

0.25 part of cetyl polyglycol ether,

3.50 parts of polyethylene glycol, and

91 parts of kaolin (particle size: 0.3-0.8 mm).

The active substance is mixed with epichlorohydrin, and dissolved in 6parts of acetone; polyethylene glycol and cetyl polyglycol ether arethen added. The solution thus obtained is sprayed onto kaolin, and theacetone is subsequently evaporated off in vacuo.

Wettable powder

The following constituents are used to produce (a) a 70% wettable powderand (b) a 10% wettable powder:

(a)

70 parts of an active substance of the formula I,

5 parts of sodium dibutyl-naphthalene sulfonate,

3 parts of naphthalenesulfonic acid/phenolsulfonic acid/formaldehydecondensate (3:2:1),

10 parts of kaolin, and

12 parts of Champagne chalk; and

(b)

10 parts of an active substance of the formula I,

3 parts of a mixture of the sodium salts of saturated fatty alcoholsulfates,

5 parts of naphthalenesulfonic acid/formaldehyde condensate, and

82 parts of kaolin.

The given active substance is absorbed onto the appropriate carriers(kaolin and chalk), and the material is subsequently mixed and groundwith the remaining constituents. Wettable powders having excellentwetting and suspension properties are obtained. It is possible to obtainfrom wettable powders of this type, by dilution with water, suspensionscontaining 0.1 to 80% of active substance, and these suspensions aresuitable for controlling weeds in crops of cultivated plants.

Paste

The following substances are used to produce a 45% paste:

45 parts of an active substance of the formula I,

5 parts of sodium aluminum silicate,

14 parts of cetyl polyglycol ether having 8 mols of ethylene oxide,

1 part of oleyl polyglycol ether having 5 mols of ethylene oxide,

2 parts of spindle oil,

10 parts of polyethylene glycol, and

23 parts of water.

The active substance is intimately mixed and ground with the additivesin apparatus suitable for the purpose. There is obtained a paste fromwhich can be produced, by dilution with water, suspensions of anydesired concentration.

What is claimed is:
 1. A herbicidal composition comprising (1) aheterocyclic ester of2-nitro-5-(o-chloro-p-trifluoromethylphenoxy)-benzoic acid of theformula ##STR29## wherein A is a branched-chain or straight-chain C₂ -C₄alkylene group,R₁ and R₂ taken together with the nitrogen atom to whichthey are attached or R₁ and a carbon atom of A taken together with thenitrogen atom to which R₁ is attached for a 3- to 7-memberedheterocyclic which optionally includes in its ring an oxygen atom, asulfur atom or the group --NR₃ -- in which R₃ is hydrogen, C₁ -C₄ alkyl,phenyl or benzyl, and R₂ when not forming part of the heterocyclic ringis hydrogen or C₁ -C₄ alkyl, and acid addition or quaternary ammoniumsalts thereof, and (2) an inert carrier.
 2. A method of controllingweeds in crop cultures which comprising applying thereto a herbicidallyeffective amount of a compound of the formula ##STR30## wherein A is abranched-chain or straight-chain C₂ -C₄ alkylene group,R₁ and R₂ takentogether with the nitrogen atom to which they are attached or R₁ and acarbon atom of A taken together with the nitrogen atom to which R₁ isattached form a 3- to 7-membered heterocycle which optionally includesin its ring an oxygen atom, a sulfur atom or the group --NR₃ -- in whichR₃ is hydrogen, C₁ -C₄ alkyl, phenyl or benzyl, and R₂ when not formingpart of the heterocyclic ring is hydrogen or C₁ -C₄ alkyl, and acidaddition or quaternary ammonium salts thereof.
 3. A method according toclaim 2 in which the compound is an acid addition or quaternary ammoniumsalt.
 4. The method according to claim 2 in which the compound is2-nitro-5-(o-chloro-p-trifluoromethylphenoxy)-benzoic acidmorpholinoprop-2'-yl ester.
 5. The method according to claim 2 in whichthe compound is 2-nitro-5-(o-chloro-p-trifluoromethylphenoxy)-benzoicacid pyrid-2'-yl-methyl ester.
 6. The method according to claim 2 inwhich the compound is2-nitro-5-(o-chloro-p-trifluoromethylphenoxy)-benzoic acid(3'-pyrid-2"-yl-propyl)ester.
 7. The method according to claim 2 inwhich the compound is2-nitro-5-(o-chloro-p-trifluoromethylphenoxy)-benzoic acid(2'-pyrrolidino-ethyl)ester.
 8. The method according to claim 2 in whichthe compound is 2-nitro-5-(o-chloro-p-trifluoromethylphenoxy)-benzoicacid (pyrid-3'-yl-methyl)ester.
 9. The method according to claim 2 inwhich the compound is2-nitro-5-(o-chloro-p-trifluoromethylphenoxy)-benzoic acid[3'-(3"-oxopyrrolidino)-propyl]ester.
 10. The method according to claim2 in which the compound is2-nitro-5-(o-chloro-p-trifluoromethylphenoxy)-benzoic acid(1'-methylpiperid-3'-ylmethyl)ester.
 11. A method according to claim 1in which the crop is soybeans or rice and the compound is appliedpost-emergently.